Schueller et al.: Using a projector and microscope to read scales from Brevoortia tyrannus and B. patronus 31 
longer stored in an outdated format. Finally, notes can be 
added to data entries in the database, along with sample 
information, and digital images of scales can be captured 
for easy reference and for training purposes within and 
across laboratories. 
Moving forward, reference collections will be a primary 
QA and QC tool for training and maintaining aging stan- 
dards (Eltink et al.?°: Campana, 2001; Morison et al., 
2005). New digital reference collections for Atlantic and 
Gulf menhaden will be composed of average quality scales 
with an annotated version to be shared with other aging 
laboratories for training purposes. A digital collection has 
longevity and ensures that all aging scales are prepared 
by the same method (Campana, 2001). Samples for the 
digital reference collection should represent multiple 
years and have 10 samples, with varying edge margins, 
from each of the age classes for each month of landings 
sampled (Eltink et al.'°). Campana (2001) suggests that a 
reference collection composed of 200—500 samples be used 
for quality control, although a training set of 100 sam- 
ples is sufficient. For exchanges, a reference collection of 
400 samples has been suggested, with possibly 150-200 
subsamples sent at a time (Eltink et al.1°. Campana, 
2001). A subsample of the samples used in this study 
could be assembled as a control collection because they 
are of unknown ages and are true representatives of the 
catch. A subsample of this collection should be aged again 
yearly by the current reader to reassess consistency, preci- 
sion, and bias of age estimates and could be used to train 
another reader (Eltink et al.'°; Campana, 2001). Collec- 
tions should be updated at regular intervals. 
Finally, the standards for determining continuity in age 
determination and for comparing between methods need 
further investigation. Sample sizes used in many studies 
are smaller than those in our study, and work to identify 
the sample size that is sufficient to answer questions of 
such examinations is greatly needed. McBride (2015), 
through simulation, tested PA, APE, ACV, and bias of 
age estimates by using different types of bias and sample 
sizes of 5 samples per age class with 20 ages. The behav- 
ior of these tests with differences in sample sizes across 
ages, meaning a more natural sample size distribution 
given common sampling protocols, would help to elucidate 
whether ages are consistent across methods. 
Acknowledgments 
We thank J. Potts, G. Nesslage, and the anonymous 
reviewers for helpful comments and suggestions on ear- 
lier drafts. This project was funded through the Improve 
a Stock Assessment Program of the Office of Science and 
Technology, National Marine Fisheries Service. 
* Eltink, A. T. G. W., A. W. Newton, C. Morgado, M.'T. G. Santamaria, 
and J. Modin. 2000. Guidelines and tools for age reading (PDF 
document version 1.0 October 2000). Eur. Fish Ageing Netw., 
EFAN Rep. 3-2000, 54 p. Eur. Fish Ageing Netw., Arendal, 
Norway. 
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